Gary Barlow vows to shake up the X Factor as he and Robbie Williams slam Simon Cowell for lack of care towards contestants

Robbie Williams and Gary Barlow have slammed Simon Cowell and the old X Factor judging panel for failing to care for contestants.

New lead judge Barlow said he was 'evolving' the show to make sure acts were properly mentored, while Williams accused Cowell of caring more about entertainment than music.

The Take That singers are in Los Angeles, where Barlow is holding his Judge's House.

Time to shake things up: Gary Barlow and Robbie Williams, seen here in LA for the X Factor, slammed Simon Cowell for not making more of an effort with finalists

He is selecting four contestants from his category - the boys - to go to the final stage, and chose his bandmate to help him make the decision.

Barlow, 40, said he was making the show more credible and vowed to have quality acts, because of his commitment to the programme.

He said: 'I want to change things this year. With three new judges, this is where there will be an evolution of the show.

'I think you are going to see for the first time real mentoring going on. With time being put into these kids, and we are going to see a better quality of acts this year because of it.'

Past contestants have criticised Cowell and the other judges for the lack of time and effort they put in to mentoring them.

Williams, 37, said: 'Gary is going to be closer than anyone has been in the past. I think that is what is needed.

No time to spare: Williams said previous judges, including Cheryl Cole, seen here during the last series, didn't give enough time to the finalists

'Previously the judges maybe gave the acts half an hour if they were lucky.

'I think the ones that are going to make it need help, and need a guiding arm put around them.'

He added that the mogul had failed to get the music on the programme right because the focus was on entertainment TV.

Williams explained: 'I love The X Factor and I love the spectacle and being entertained but they haven't got the music right.

Failing the talent: Both Barlow and Williams said Simon Cowell was more concerned about the entertainment than the music

'I don't know if that's because of the X Factor people or if the pool of songwriters has dried up. But Gary knows what he is doing.'

In a shake-up of the show, Barlow said he had already worked out a itinerary for his acts going through to the live finals.

He said: 'I have got a weekly schedule for the boys. This is all I am going to do. So all my attention will wear them down. They are going to get a shock these boys, because I have really high standards.

'I want to feel good after this. If they go out I want them to think (they) learned a lot and (felt) supported and helped by my mentor.

The star said fellow judges Kelly Rowland and Tulisa Contostavlos had also vowed to spend all their time helping their acts.

Barlow confessed rivalry between him and Cowell was becoming increasingly bitter and said he was threatened by the new line-up's success.

The series is averaging in excess of 11million viewers a week and he said: 'Those ratings are more bitter than sweet for Simon. Obviously (now) we want to beat the American X Factor, we want to be more popular, that's everyone's goal.'

Cowell has staked his reputation on the U.S X Factor - which will begin broadcasting later this month.

Barlow said Williams was the 'obvious choice' to be his adviser.

The stars ended a 15-year feud last year, and have now toured together in Take That, and are working on Williams's new album.

An evolution: Barlow (far right) says he and the new judges can make a real difference this year

Barlow said: 'He seemed like the obvious one. I knew he loved the show. He has done since day one. When we were on tour I said (to him): 'I need someone for judges houses what do you reckon?' thinking he wouldn't be too into it. And he was like "please let me".'

Williams even invited Barlow to stay at his Los Angeles house ahead of deliberations.

Barlow said: 'I’ve been staying with him all week and it’s bloody brilliant. I sat back stage and watched the monitor and it was him back as him. It’s lovely.'

But he admitted he could not rely on him 100 per cent, because with Williams 'you never know what you are going to get each morning'.